1. Field of the Invention
The present invention relates to a suspension substrate used for a magnetic head suspension for a HDD, and, particularly, to a suspension substrate having reduced strain.
2. Description of the Related Art
In recent years, there have been great demands for increases in the amount of information processing and in information processing speed of a personal computer with, for example, the distribution of Internet. Along with this, it has become necessary for hard disc drives (HDD) incorporated into a personal computer to increase its capacity and its information communication speed. The magnetic head suspension used in this HDD is provided usually with a suspension substrate mounted with a magnetic head. Also, the suspension substrate is formed with wirings (read wiring and write wiring) made of conductive thin films to connect this magnetic head with the read/write wirings of the magnetic disc device.
In current suspension substrates, plural (for example, two) wirings having a narrow width are generally formed on the same plane of the insulation part. On the other hand, a suspension substrate is known in which plural wirings having a wide width are not formed on the same plane but are laminated through an insulation part. In, for example, Japanese Patent Application Publication (JP-A) No. 10-3632, there is disclosed a magnetic head suspension having a gimbal suspension obtained by laminating two or more wirings having a wide width through an insulation part. Also, in JP-A No. 9-22570, there is also disclosed a head assembly obtained by laminating wirings having a wide width through an insulation part. Further, in JP-A No. 8-102162, a magnetic head suspension is disclosed in FIG. 1, in which a wiring pattern comprising an effective wiring 3 and a dummy wiring pattern 2 which are substantially symmetric with respect to the suspension center line 4 is arranged on a spring part 1c of a suspension body 1.